A device with an opening organ for opening fiber bales with two rotating opening rollers is known from the German patent Specification DE-33 34 222 C2, with which the opening organ is moved to and fro over the surface of the fiber bales for opening the fiber flocks and with every passage penetrates into the fiber bale with a specified depth of penetration, in order to give the opening roller the opportunity to open fiber flocks from the surface, which are subsequently given over to a pneumatic removal and conveying system such as a hoisting shaft.
Further, it is known from West German Utility Patent No. 87 12 308.8, that with a previously described opening organ with two rotating rollers, instead of the horizontal passage of the opening rollers for opening fiber flocks from the surface of the fiber bales, the opening organ opens the fiber flocks in a direction of movement inclined to the horizontal from a correspondingly inclined surface of the fiber bales.
In opposition to the system described in the DE-33 34 222 in which the fiber bales are arranged in a stationary position, according to the description of the aforesaid utility patent, the fiber bales are moved to and fro on the conveyor against the opening organ, so that the opening organ always opens fibers from the inclined surface in the same movement region.
It is known in practice that with such double roller bale openers the rollers are contra-rotating, whereby seen in the direction of movement in each case, the front opening roller rotates with a so-called synchronism with the direction of movement, in order to open the fibers from the surface in this synchronism. The rear rollers, seen in the direction of movement, rotate correspondingly in the opposite sense and open the fiber flocks from the same surface in the contra-rotating cutting system.
It is now known, that the opening of fiber flocks in the aforesaid opposite sense has a lower opening efficiency from the point of view of quantity than a roller which turns in contra-rotation.
Likewise, an opening organ with an opening roller is known, in which the sense of rotation is reversible, so that the opening roller may be moved in the synchronous sense at all times.
With the known double roller arrangement, it is possible to open flocks with the two and fro passage of the opening organ without it being necessary to change the sense of rotation of the rollers, because the two oppositely rotating rollers can be rotated in such directions that, whichever roller is the leading roller when the head or organ is moving in a given direction, that roller will contact the bales with a directional component opposed to the direction of bodily movement of the head. That is, the front roller always rotates in synchronism directionally with the linear movement of the head as a whole. An increase in the opening performance, compared with the single roller opening organ mentioned, cannot really be attained however, because of the lower efficiency (with reference to quantity) of the contra-rotating opening roller.
An improvement of performance resides in the possibility of allowing both opening rollers to rotate in synchronism for each direction of movement. However, this implies that for the return passage of the rollers, an opposite sense of rotation is given or that the opening organ is lifted from the surface, so that fiber flocks can be opened in one direction. The increase in performance, however, is itself a little problematical in the latter case with a rapid return passage, as according to the length of the row of bales, a time interval must be taken into account, during which no fiber flocks are opened.
A further means of increasing the performance exists, as is known, by increasing the length of the rollers. This is possible with opening organs which have either a single roller or two rollers. The disadvantage of such a measure exists, however, in the broad working range of the stand holding the opening organ, which results in a higher mechanical load of the entire system.
It would be desirable to increase, independently of the length of the opening rollers, the opening performance achieved in horizontal opening accordingly to DE-33 34 222 or inclined opening according to DE-GM-87 12 308.